Added also the broken flag on savephonopy

Author: mesonepigreco

cellconstructor/Phonons.py

@@ -1286,6 +1286,7 @@ def save_phonopy(self, path = ".", supercell_size = None, units_ev_ang2 = True,
 
 
         """
+        raise NotImplementedError("This subroutine to save in phonopy format is broken. Use CC.Methods.tensor2_to_phonopy_fc2 instead.")
         if supercell_size is None:
             supercell_size = self.GetSupercell()